Processes for the preparation of 4-alkoxy-3-(acyl or alkyl)oxypicolinamdes
A fungicidal 4-methoxy-3-acetyloxypicolinamide may be conveniently prepared in processes that include the coupling together of 4-methoxy-3-acetyloxypicolinic acid or 4-methoxy-3-hydroxypicolinic acid with a key 2-aminopropanoate ester derived from a 1,1-bis(4-fluorophenyl)propane-1,2-diol.
1. A process for the preparation of the compound of Formula C
wherein X is Cl, Br, HSO 4 , H 2 PO 4 or CH 3 SO 3 ;
which comprises the following steps:
a) creating a first mixture containing the compound of Formula G,
an acylating agent and a base;
b) adding the compound of Formula H
to the first mixture to form a second mixture;
c) isolating the compound of Formula I
from the second mixture;
d) creating a third mixture containing the compound of Formula I, an acid and a reducing agent;
e) isolating the compound of Formula J from the third mixture;
f) creating a fourth mixture containing the compound of Formula J and a strong acid;
wherein the strong is HCl, HBr, H 2 SO 4 , H 3 PO 4 or CH 3 SO 3 H; and
g) isolating the compound of Formula C from the fourth mixture.
2. The process of claim 1 wherein the acylating agent is an acid chloride of the Formula RCOCl, wherein R is a C 1 -C 4 alkyl.
3. The process of claim 1 wherein the first mixture further comprises a solvent selected from the group including, DCM, DCE, ACN, isopropyl acetate, THF, 2-MeTHF, and mixtures thereof.
4. The process of claim 1 wherein the base may be selected from the group including TEA, DIPEA, pyridine, and mixtures thereof.
5. The process of claim 1 further comprising the addition of DMAP (4-(dimethylamino)pyridine) to the first mixture.
6. The process of claim 1 wherein the acid in the third mixture is trifluoroacetic acid or methanesulfonic acid.
7. The process of claim 1 wherein the reducing agent is selected from the group including sodium borohydride, sodium triacetoxyborohydride, and an organosilicon hydride.
8. The process of claim 7 wherein the organosilicon hydride is selected from the group including triethylsilane, poly(methylhydrosiloxane) and 1,1,3,3-tetramethyldisiloxane.
9. The process of claim 1 wherein the fourth mixture is maintained under anhydrous conditions.
10. A process for the preparation of the compound of Formula C
wherein X is Cl, Br, HSO 4 , H 2 PO 4 or CH 3 SO 3 ;
which comprises the following steps:
a) creating a first mixture containing the compound of Formula H
a reducing agent and an acid;
b) isolating the compound of Formula K from the first mixture;
c) creating a second mixture containing the compound of Formula G,
an acylating agent and a base;
f) adding the compound of Formula K to the second mixture to form a third mixture;
g) isolating the compound of Formula L from the third mixture;
h) creating a fourth mixture containing the compound of Formula L and a strong acid;
wherein the strong acid is HCl, HBr, H 2 SO 4 , H 3 PO 4 or CH 3 SO 3 H; and
i) isolating the compound of Formula C from the fourth mixture.
11. The process of claim 10 wherein the acid in the first mixture is trifluoroacetic acid or methanesulfonic acid.
12. The process of claim 10 wherein the reducing agent is selected from the group including sodium borohydride, sodium triacetoxyborohydride, and an organosilicon hydride.
13. The process of claim 12 wherein the organosilicon hydride is selected from the group including triethylsilane, poly(methylhydrosiloxane) and 1,1,3,3-tetramethyldisiloxane.
14. The process of claim 10 wherein the acylating agent is an acid chloride of the Formula RCOCl, wherein R is a C 1 -C 4 alkyl.
15. The process of claim 10 wherein the second mixture further comprises a solvent selected from the group including, DCM, DCE, ACN, isopropyl acetate, THF, 2-MeTHF, and mixtures thereof.
16. The process of claim 9 wherein the base in the second mixture may be selected from the group including TEA, DIPEA, pyridine, and mixtures thereof.
17. The process of claim 10 further comprising the addition of DMAP (4-(dimethylamino)pyridine) to the second mixture.
18. The process of claim 10 wherein the fourth mixture is maintained under anhydrous conditions.